Probably. The way copyright law interacts with the Constitution is... - The Constitution itself says Congress can enact copyright law, as long as the laws them

Probably. The way copyright law interacts with the Constitution is... - The Constitution itself says Congress can enact copyright law, as long as the laws themselves have a finite copyright term[0] - As amended, the Constitution has a prohibition on "Congress" (state actors) making laws that circumscribe speech - Since the intent of the 1st Amendment was not to immediately repeal the Copyright Clause, both provisions are valid; the 1st Amendment only protects novel acts of speech. The speaker is free to prohibit further speech that infringes upon their own. - However, said speakers (copyright owners) are not free to prohibit any and all speech that touches their own. Only stuff that actually harms their monopoly on copying. Fair use is how copyright law passes constitutional scrutiny. - Because DMCA 512 contains provisions for counter-notices and legal penalties for misidentification; people attempting to use copyright as a censorship tool can be punished for doing so. - The SMART Act appears to amend DMCA 512, so said provisions would still apply. It also does not mandate upload filters on it's own, it just says the Copyright Office may decide to do so. Whether or not an upload filter would violate the 1st would require SCOTUS to find that the DMCA counternotice provision is too burdensome for speakers making fair uses of copyrighted content. I'm not sure that would fly, even with very strict upload filters everywhere. Courts don't like having to make emergency judgments on these sorts of things, especially in situations where the remedy to the problem is "just send a counternotice". If you were able to demonstrate in court that a particular mandate for upload filtering unnecessarily burdened speakers, then you probably might be able to overturn a specific Copyright Office SMART Act ruling. However, that would be a huge pain in the ass at best. [0] It is currently undecided if this includes lim ©->; the closest attempt to apply "limited times" (Eldred v. Ashcroft) to asymptotic infinities failed. The thing about the Copyright Term Extension Act is that it wasn't just a blanket retroactive extension of copyrights; there were actual Germany-flavored reasons to do so.